\documentclass{article}
% http://www.zedimage.com/pms-cmyk-hex.php
% latex package spotcolor
%\pdfminorversion=4
%\pdfobjcompresslevel=0
\usepackage[paperwidth=1in,paperheight=1in]{geometry}
\usepackage{xcolor}
\usepackage{tikz}
\usetikzlibrary{fadings}
\definecolor{UQpurple}{HTML}{51247A}
\definecolor{lightpurple}{HTML}{962A8B}
\pagestyle{empty}
\begin{document}
  \begin{tikzpicture}[remember picture,overlay]
    \node at (current page.north west)
      {\begin{tikzpicture}[remember picture,overlay]
      \fill[lightpurple] (0,0) rectangle (\paperwidth,-\paperheight);
        \fill[UQpurple,path fading=east] (0,0) rectangle (\paperwidth,-\paperheight);
       \end{tikzpicture}
      };
  \end{tikzpicture}%
\end{document}